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Path Tracing in Unity using Octane

Unity recently added support for Path Tracing using Octane so I decided to give it a try. I was in the beta program for a few months and it turned out the A320 CAD model in Unity caused quite a few problems due to the large amount of materials used. But eventually it did work.

Here is a sample render. Right click->View Image to expand. (WordPress really has to make this easier)

The images below are tone mapped in Photoshop. This looks a bit better.

Although it works pretty much out of the box, I discovered a few issues:

-All materials appear slightly more rough when rendered with Octane. Unfortunately there is no global slider available to fix this issue.

-Although the renderer is full HDR (32 bit float RGBA which is 128 bit per pixel), it requires careful tweaking of the sun intensity, exposure, gamma, sky turbidity, and tone mapping in order to avoid white highlights or the entire scene looking too dark. This is a common issue with renderers and is described in detail here. You can also work around this problem by saving the render as an 16 bit EXR and then modifying it in Photoshop but that solution is less than ideal. An out of the box solution which is more physically inspired would be more ideal.

-Currently there are a few bugs which require some workarounds. This includes GameObjects with disabled MeshRenderers still being rendered and spot lights casting shadows.

-A model designed for realtime rendering does not necessarily look good with Path Tracing. This is not the fault of the Path Tracer but due to the fact that flat geometry with detail in AO maps is not rendered. Have a look at the screws on the FCU and you can see that it lacks AO. I did not try enabling the AO maps (not sure if that is possible) but that would make other geometry look worse due to quality issues. My AO mapse are just not designed for close up renders.

Even with the current issues, it is still an easy and quick way to get a nice looking render. And it is free 🙂